Broad Objective: The overall aim is to produce a family of radioactive inert indicator substance for off-the-shelf use in evaluating alterations in intestinal absorption. Radioactive inert indicator isotope will be "packaged" in an inert insoluble substance. The packaged isotope can be produced with a density close to that of solid food in any desired particle size range from 2 to 100 plus or minus micra in diameter. The influence of the particles size and specific gravity on the rate and uniformity of transit through the bowel will investigated. Appropriate radioactive labels incorporated in appropriate size particles will be selected for use as radioactive inert indicators to measure the absorption of fat, labelled vitamin, and various essential minerals from the bowel. The encapsulation process and the extend the range of indicators available for the measurement of intestinl absorption and broaden the number of elements available (wider spectra choice).